Conventional poles and other structures for magnetic recording heads can be fabricated in a number of ways. For example, FIG. 1 is a flow chart depicting a conventional method 10 for fabricating a chemical mechanical planarization (CMPS) support layer of a magnetic recording transducer using a conventional mill-and-refill process. For simplicity, some steps are omitted. FIGS. 2-5 are diagrams a depicting conventional transducer 50 as viewed from the air-bearing surface (ABS) during fabrication. For clarity, FIGS. 2-5 are not drawn to scale. The conventional transducer 50 may be coupled with a slider to form a write head. In addition, a read transducer (not shown) may be included to form a merged head. For simplicity, only a portion of the conventional transducer 50 is shown.
A conventional magnetic seed layer is provided on a planarized underlayer, via step 12. In some transducers, the conventional magnetic seed layer may be used as a pole. The conventional seed layer is used in fabricating a magnetic pole, for example the main pole for a perpendicular magnetic recording transducer. The magnetic seed layer is generally blanket deposited across both a device region, in which the structure is to be fabricated, and a field region away from the device region. However, for other structures, the layer deposited may reside only in the device region. A photoresist mask is provided on the conventional seed layer, via step 14. FIG. 2 depicts the conventional transducer 50 after step 14 is completed. Thus, an underlayer 52, a conventional seed layer 54, and photoresist mask 56 are shown. The underlayer 52 is typically planarized prior to deposition of the conventional seed layer 54. Consequently, the upper surface of the conventional underlayer 52 is substantially flat. The photoresist mask 56 resides substantially in the device region 60. However, the conventional seed layer 54 extends to the field regions 58.
The conventional seed layer is milled with an over-mill condition, via step 16. Because the photoresist mask 56 covers the device portion 60, only the portion of the conventional seed layer 54 in the field regions 58 is removed. The over-mill condition is used to ensure complete removal of the portion of the conventional seed layer 54 in the field regions 58. FIG. 3 depicts the conventional magnetic recording transducer 50 after step 16 has been performed. Because an over-mill condition was used, only the portion of the conventional seed layer 54′ in the device region 60 remains. The remainder of the conventional seed layer 54 has been removed.
The magnetic transducer 50 is refilled with alumina, via step 18. The refill is performed while the photoresist mask 56 remains in place. FIG. 4 depicts the conventional magnetic recording device after step 18 has been performed. Thus, alumina layer, including portions 62A, 62B, and 62C, is shown. The alumina layer is shown with portions 62A and 62C residing in the field regions 58 as well as a portion 62B residing on the photoresist mask 56 in the device region 60. The portions 62A and 62C of the alumina layer are to serve as the CMPS layer.
The photoresist mask 56 may be stripped and processing of the device continued, via step 20. FIG. 5 depicts the conventional magnetic transducer 50 after stripping of the photoresist mask in step 20 has been completed. Thus, the seed layer 54′ in the device region 60 and the alumina 62A and 62B in the field regions 58 remain. Thus, a CMPS layer has been fabricated. Additional structures (not shown) such as a magnetic pole(s), coil(s), shields, or other components may also be fabricated.
Although the conventional method 10 may be used in providing the conventional transducer 50, there may be drawbacks. The over-mill condition in step 16 allows for complete removal of the conventional seed layer. However, the over-mill condition also results in the underlayer 52 being milled. The portions of the underlayer 52′ exposed during the milling, particularly by the over-mill condition, are damaged. As a result, the surface of the underlayer 52′ in the field regions 58 is no longer planar. Subsequent layers, such as the alumina 62A and 62B, may also have a topology that is not flat in the field regions 58. Stated differently, there is a greater variation in the step height for the alumina 62A and 62B, which serve as a CMPS layer. This variation may adversely affect the write track width uniformity, result in poor uniformity of the pole trim, and reduced CMP uniformity. Other structures fabricated using processes similar to the method 10 may suffer from similar drawback.
Accordingly, what is needed is an improved method for fabricating structures in a magnetic transducer.